1. Field of the Invention
The present invention relates to a structure for mounting a flexible printed board and an optical pick up having the flexible printed board mounting structure. More specifically, the present invention relates to a structure in which a light-receiving IC is mounted on a flexible printed board is installed on the main body of an optical pickup.
2. Background Information
Driving devices for optical disks generally include an optical pick up. Such optical pick up generally includes a bi-axial actuator and a slide base that houses the bi-axial actuator. The slide base has an objective lens through which light from a light source such as a semiconductor laser is collected on the optical disk. Photodiode is an example of the known light source. The bi-axial actuator shifts the objective lens in two directions (focus direction and tracking direction) to focus the light on the surface of the optical disk.
An example of the flexible printed board in accordance with the conventional art is shown in FIGS. 7 and 8. The flexible printed board 160 of this conventional art is to be attached to a sliding base 122, which has a mounting hole 140 for mounting a photodiode PD on the side surface 131. The mounting hole 140 has a vertically symmetrical shape relative to a horizontal line. A positioning hole 142 is formed on the sliding base 122 so as to be connected with the mounting hole 140. This positioning hole 142 is adapted to fit over the lens 144 of the photodiode PD. The lens 144 has a substantially hemispherical shape. Two grooves 146, 146 are formed in the mounting hole 140, on which an adhesive B is to be applied. An adhesive surface 162 of the flexible printed board 160 is attached to the peripheral surface 150 around the mounting hole 140 and to the bottom surface 132 of the sliding base 122. An example of such structure is disclosed in, for example, Japanese Patent Application Publication No. 7-263836.
In this structure, as shown in FIGS. 7-8, the photodiode PD is positioned at the attachment place (the mounting hole 140 and the positioning hole 142) by bending the flexible printed board 160 at a border 163 by about 180 degrees. Here, the distance LC between the border 163 and the upper edge of the photodiode PD is substantially the same as the distance LE between the upper edge of the side surface of the sliding base 122 and the upper edge of the mounting hole 140. In other words, the photodiode PD of the flexible printed board 160 is disposed in the attachment place by tightly attaching the bent portion of the flexible printed board 160 to the side surface of the sliding base 122. (ADDED btw 0002-0003)
Such structure, however, requires high precision in manufacturing and positioning of the components. Accordingly, it has been a problem that the mounting position of the lens 144 of the photodiode PD tends to be misaligned.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for improved flexible printing board mounting structure and optical pick up that overcome the problems of the conventional art. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.